A fresh radioactive sample is given at $t = 0$. Its decay fraction are $\frac{1}{5}$ at $t_1$ instant and $\frac{4}{5}$ at $t_2$ instant. Its mean life is
A fresh radioactive sample is given at $t = 0$. Its decay fraction are $\frac{1}{5}$ at $t_1$ instant and $\frac{4}{5}$ at $t_2$ instant. Its mean life is
- A
$\frac{{{t_2} - {t_1}}}{{\ln \,2}}$
- B
$\frac{{{t_2} - {t_1}}}{{\ln \,4}}$
- C
$\frac{{{t_2} - {t_1}}}{{\,2}}$
- D
$\frac{{{t_2} - {t_1}}}{{\,4}}$
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- [AIEEE 2011]
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